Seok-Kwon Kang

Field Trapping of Chrysopa cognata (Neuroptera: Chrysopidae) with Aphid Sex Pheromone Components in Korea

Abstract Attraction of Chrysopa cognata (McLachlan) adults to two major aphid sex pheromone components, (-)-(1 R ,4a S ,7 S ,7a R )-nepetalactol (NL) and (+)-(4a S ,7 S ,7a R )-nepetalactone (NN), was investigated in field experiments in Korea. C. cognata adults were much more highly attracted to NL than to NN. Even though NN also attracted significantly more C. cognata adults than did solvent control, there were no synergistic or additive effects on the trappings by NL. In a series of trapping experiments with blends of the two chemicals, C. cognata numbers trapped tended to increase with the content of NL, but never more than that by NL alone. As the amount of aphid sex pheromone components increased, more C. cognata were captured. However, the period of attraction for NL significantly decreased with time and after 50 days few C. cognata adults were attracted. C. cognata adults were mainly captured during the night and only a few were attracted in daytime during the late fall period. Even during the night, most of C. cognata were attracted from about 7:00 PM to 11:30 PM with apparently a longer period of activity in the summer than in the fall with an intermediate activity period in the spring. C. cognata adults caught in traps throughout the trap experiments were almost only males, in agreement with electroantenogram (EAG) results which showed that only male adults responded. The EAG response was stronger to NL than to NN. In addition to C. cognata , a few male adults of Chrysopa formosa (Brauer) and Chrysopa phyllochroma (Wesmael) were also captured in field pheromone traps.

High-level expression of a foreign gene by a recombinant baculovirus with an expanded host range

The usefulness of host range expanded viruses as an expressionvector system was investigated by following the expression ofthe E. coli lacZ gene. The host range expanded recombinantviruses were obtained from Sf-21 or BmN-4 cells coinfected withAutographa californica and Bombyx mori nuclearpolyhedrosis viruses. Among the host range expanded viruses,RecB-8 and RecS-B6 have similar enzyme digestion profiles butdifferent infection characteristics in cells. Therefore, tostudy the foreign gene expression efficiency of these twoviruses, we constructed recombinant viruses RecB8-LacZ andRecSB6-LacZ containing the lacZ gene instead of the polyhedringene. Also, the host range expanded recombinant AcNPV, Bac-BH,containing lacZ gene in the polyhedrin gene locus was constructedby substitution of the 0.6 kb region within the helicase gene ofBacPAK6 with that of BmNPV. β-Galactosidase expressionefficiency by these viruses were determined and compared in Sf-21and BmN-4 cells. The result showed that Bac-BH has highexpression efficiency only in Sf-21 cells, whereas RecB8-LacZhas high expression efficiency both in Sf-21 and BmN-4 cells.Also, in BmN-4 cells, β-galactosidase expressionefficiency of RecB8-LacZ was higher than that of recombinantBmNPV (BmK1-LacZ containing lacZ gene in polyhedrin gene locus).In addition, the expression efficiency was not correlated withvirus titer.